ios - 音频不在后台模式下播放

Question

当我的应用进入后台模式时，我想在 5 秒 后播放“音频”。 NSTimer 正确触发。 5 秒后，我得到了 NSLog(@"repeat");。但是，有些音频没有播放。我在我的目标中启用了背景模式。我尝试了许多其他解决方案，在 stackoverflow 中找到，但没有成功。任何人都可以为我提供正确的解决方案。

在我的 appdelegate.h 文件中:

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>

@interface AppDelegate : UIResponder <UIApplicationDelegate>
{
    NSTimer* timer;
}

@property (strong, nonatomic) UIWindow *window;

@property (nonatomic, strong) NSString *musicName;
@property (nonatomic, strong) AVAudioPlayer *audioPlayer;

在我的 appdelegate.m 文件中:

#import "AppDelegate.h"

@interface AppDelegate ()

@end

@implementation AppDelegate

@synthesize
musicName,
audioPlayer;

-(void) playAlarmSound
{
    musicName = @"note3BreakOf.mp3";
    // Construct URL to sound file
    NSString *path = [NSString stringWithFormat:@"%@/%@", [[NSBundle mainBundle] resourcePath], musicName];
    NSURL *soundUrl = [NSURL fileURLWithPath:path];

    // Create audio player object and initialize with URL to sound
    audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:soundUrl error:nil];
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    [self playAlarmSound];
    return YES;
}

-(void)methodRunAfterBackground
{
    [audioPlayer play];
    [timer invalidate];
    NSLog(@"repeat");
}

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    UIApplication *app = [UIApplication sharedApplication];

    //create new uiBackgroundTask
    __block UIBackgroundTaskIdentifier bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
        [app endBackgroundTask:bgTask];
        bgTask = UIBackgroundTaskInvalid;
    }];

    //and create new timer with async call:
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        //run function methodRunAfterBackground
        timer = [NSTimer scheduledTimerWithTimeInterval:5 target:self selector:@selector(methodRunAfterBackground) userInfo:nil repeats:NO];
        [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];
        [[NSRunLoop currentRunLoop] run];
    });
}

Answer 1

您需要将“playsAudio”添加到您的 plist 并设置

• AVAudioSession sharedInstance 类别为:AVAudioSessionCategoryPlayback
• AVAudioSession 共享实例设置事件:是
• UIApplication sharedApplicationbeginReceivingRemoteControlEvents

似乎其中一些可能已被弃用，请查看 here

在 Objective-C 中:

[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];
[[AVAudioSession sharedInstance] setActive: YES error: nil];
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];